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Severe combined immunodeficiency

Related Terms

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Background

  • Severe combined immunodeficiency (SCID) is a genetic disorder of the immune system that occurs when the T-lymphocyte system does not function properly. SCID is the most severe type of primary immune deficiency diseases. Primary immunodeficiencies are disorders that occur because part of the body's immune system does not function properly. Unlike secondary immunodeficiencies, which are caused by external factors like viruses or chemotherapy, primary immunodeficiencies are caused by problems that originate within the patient's own body. SCID is usually diagnosed during childhood. A milder form of T-lymphocyte dysfunction causes combined immunodeficiency, which is typically diagnosed in adults.
  • The immune system protects the body from harmful antigens (foreign substances that enter the body) like bacteria, viruses, fungi, or parasites. A specialized tissue inside bones called marrow produces immune system cells, which are also called stem cells. These stem cells then develop into B-lymphocytes, T-lymphocytes and natural killer (NK)-lymphocytes and phagocytes. All of these cells produce proteins that help them detect antigens that enter the body. The cells and proteins are spread throughout the body to protect the body from diseases and infections.
  • There are three types of T-lymphocytes: T-helper cells, cytotoxic T-cells, and regulatory (T-reg or T-suppressor) T-cells. When an antigen enters the body, T-helper cells direct B-lymphocytes (B-cells) to make antibodies against it. These antibodies then bind to the foreign substance, which is called an antigen. This binding tells the T-cytotoxic cells to destroy the unwanted antigen. T-reg cells direct the resolution of the immune system response, which means they "turn off" the immune response.
  • The defining characteristic of SCID is always a severe defect in T-cell production and function. Patients also have dysfunctional B-lymphocytes, which may or may not be caused by the dysfunctional T-cells. Some genetic types of SCID also cause a shortage of NK-cell production as well. Consequently, SCID patients produce little or no antibodies, and they are extremely vulnerable to developing opportunistic infections (infections that occur in individuals with weakened immune systems).
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Causes

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Symptoms

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Diagnosis

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Treatment

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Integrative Therapies

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Prevention

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Author Information

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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.